Just a FYI. I posted about Calligra some time ago to mention Calligra Author, a word processor that can export directly to epub. I don't use it myself (I like to write in plain text), but Author and the rest of the Calligra Suite is a nice project. It's noteworthy if only for heralding the news that there's "more than one way to do it" when it comes to word processing.
Here's a link: Calligra 2.6 Released.